1. The transaction was executed in multiple trades at prices ranging from $17.25 to $17.94. The price above reflects the weighted average price. Detailed information regarding the number of shares transacted at each separate price will be provided upon request by the Commission staff, the Issuer or a security holder of the Issuer.

2. The securities are directly held by Perceptive Life Sciences Master Fund Ltd. (the "Master Fund"). Perceptive Advisors LLC (the "Advisor") serves as the investment manager of Master Fund. Joseph Edelman is the managing member of the Advisor. Each of Mr. Edelman and the Advisor disclaims, for purposes of Section 16 of the Securities Exchange Act of 1934, beneficial ownership of such securities, except to the extent of his/its indirect pecuniary interest therein, and this report shall not be deemed an admission that either Mr. Edelman or the Advisor is the beneficial owner of such securities for purposes of Section 16 or for any other purposes.